Method of producing 7{62 -acylamido-3-methylceph-3-em-4-carboxylic acid esters and catalysts therefor

ABSTRACT

The invention relates to a process for the preparation of 7 Beta -acylamido-3-methylceph-3-em-4-carboxylic acid esters from compounds of the penicillin type, in particular, 6 Beta acylamido penicillanic acid 1-oxide esters, in the presence of a catalyst selected from a mono-O-substituted orthophosphoric acid, an 0,0-di(aryl substituted) orthophosphoric acid, a salt or complex formed from a nitrogen base having a pKb of not less than 4 and a mono-0-substituted orthophosphoric acid or an 0,0-di(aryl substituted) orthophosphoric acid. The salt or complex may be formed in situ in the reaction mixture.

United States Patent 1 Graham et al.

[4 1 Apr. 3, 1973 [54] METHOD OF PRODUCING 7B-ACYLAMIDO-3-METHYLCEPH-3-EM-4- CARBOXYLIC ACID ESTERS AND CATALYSTSTHEREFOR [75] Inventors: William Graham, Pinner; Lewis A. Wetherill,North Wembley, both of England 73 Assignee: Glaxo Laboratories Limited,Greenford, Middlesex, England 22 Filed: Mar. 10, 1970 [21] Appl.No.:18,284

[30] Foreign Application Priority Data Dec. 5, 1969 Great Britain..59,450/69 [52] US. Cl. ..260/243 C, 424/246 [51] Int. Cl. ..C07d 99/24[58] Field of Search "260/243 C [56] References Cited UNITED STATESPATENTS 3,275,626 9/1966 Morin et al. ..260/243 C PrimaryExaminer-Nicholas S. Rizzo Attorney-Bacon &- Thomas [57] ABSTRACT Theinvention relates to a process for the preparation of7B-acylamido-3-methylceph-3-em-4-carboxylic acid esters from compoundsof the penicillin type, in par- 10 Claims, No Drawings METHOD OFPRODUCING 7B-ACYLAMlDO-3- METHYLCEPH-3-EM-4-CARBOXYLIC ACID ESTERS ANDCATALYSTS THEREFOR This invention is concerned with an improved processfor obtaining cephalosporin compounds. In particular the invention isconcerned with the conversion of penicillin type compounds intocephalosporin type compounds.

The compounds referred to in this specification are generally named withreference to penicillanic acid and cepham. Penicillanic acid has thestructure:

(see J.A.C.S. 1962, 84, 3,400 and J. Chem. Soc. 1965, 5,031). The termcephem refers to the basic cepham structure with a single double bond.

Cephalosporin antibiotics are of great interest in that a number of themare of value in the treatment of infections caused by pathogenicbacteria some of which are resistant to other antibiotics. Penicillincompounds are, currently, produced in greater quantities on anindustrial scale than are cephalosporin compounds and with thecontinually increasing interest in cephalosporin compounds it is highlydesirable to have available alternative techniques for producingthelatter such as a simple process for converting compounds of thepenicillin type into cephalosporins.

The invention is thus principally concerned with the conversion offl-acylamidopenicillanic acid l-oxide esters into7/3-acylamido-3-methylceph-3-em-4-carboxylic acid esters.

In U.S. Pat. No. 3,275,626 there is described a general method forpreparing antibiotic substances, including cephalosporins, whichcomprises heating a socalled penicillin sulphoxide, under acidconditions, to a temperature of from about 100C to about 175C.

It is an object of the invention to provide an improved process for therearrangement of penicillin compounds to cephalosporin compounds. Wehave found that the rearrangementcan be effected in good yields by meansof certain acids and certain derivatives thereof which exist as salts orcomplexes. It is not certain in each instance whether they are truesalts or complexes. For convenience we have described them as beingsalts although it should be understood that the term salts isinterchangeable with complexes. Moreover, under the conditions of thereaction the salt or complex may exist in a dissociated form.

According to anembodiment of the present invention therefore there isprovided a process for the preparation of7B-acylamido-3-methylceph-3-em-4- carboxylic acid esters comprisingrearranging a 6B- acylamidopenicillanic acid l-oxide ester (referred toherein for convenience as the penicillin oxide) in the presence of acatalyst selected from a mono-O-submono-O-substituted orthophosphoricacid or an 0,0-

di(aryl substituted) orthophosphoric acid, which salt may be formed insitu in the reaction mixture, or a mixture of two or more of saidcatalysts.

The process according to the invention is advantageous as compared withthe use of orthophosphoric acid from the point of view of ease andeconomy of operation and/or increased yields. Furthermore the processaccording to the invention may give rise to end products of high purity.

The mono-O-substituted orthophosphoric acid may be an aliphatic,araliphatic or aryl dihydrogen phosphate, the aliphatic, araliphatic oraryl group of which may be a hydrocarbon group, e.g. an alkyl group suchas a lower alkyl group, a phenylalkyl group such as a phenyl lower alkylgroup or a phenyl group, or such a hydrocarbon group substituted by oneor more atoms or groups such as a halogen atom or a nitro group.Examples of aryl dihydrogen phosphates include phenyl dihydrogenphosphate, p-nitrophenyl dihydrogen phosphate and dihydrogen phosphatewhilst an example of an aliphatic dihydrogen phosphate is2,2,2-trichloroethyl dihydrogen phosphate.

The 0,0-di(aryl substituted) orthophosphoric. acid may be substituted byphenyl groups or by phenyl groups substituted in turn by one or moreatoms or groups such as a halogen atom or a nitro group. An example of adiaryl hydrogen phosphate is his (4- nitrophenyl) hydrogen phosphate.

The nitrogen base may be either inorganic or organic. The expressionnitrogen base is used herein as a convenient expression for a basicsubstance containing nitrogen although it may include other hetero atomse.g. oxygen. We prefer however to use organic amines. Bases which may beused have a pKb for protonation of not less than 4 ie. as measured inwater at 25C). The base may be a polyfunctional base having a nitrogenfunction with such a pKb for the first protonation step. The basespreferably have a pKb in water of not less than 7.

The organic base may be primary, secondary or tertiary; however, weprefer to employ weak tertiary organic bases. Illustrative of suchtertiary organic bases are the unsaturated heterocyclic bases such aspyridine, quinoline, isoquinoline, benzimidazole. and homologues and/orsubstituted derivatives thereof, for example the alkyl substitutedpyridines and quinolines such as a-, 3-, and 'y-picolines and 2- and4-methylquinolines. Other substituted heterocyclic bases which may beused include those substituted by halogen (e.g. chlorine or bromine),acyl (e.g. formyl or acetyl), acylamido (e.g. acetamido), cyano,carboxy, aldoximino and the like. 7

Other organic bases which may be used include aniline and nuclearsubstituted anilines such as halogeno anilines (e.g. o-chloroaniline,mchloroaniline and p-chloroaniline); lower alkyl anilines (e.g.o-methylaniline and m-methylaniline); hydroxyand lower alkoxyanilines(e.g. o-methoxyaniline and m hydroxyaniline); nitroanilines (e.g.m-nitroaniline) and carboxyanilines (e.g. m-carboxyaniline) as well asN- lower alkyl anilines (e.g'. N-methylaniline).

2-chloromethyl-4-nitrophenyl Preferred classes of salts or nitrogenbases are those obtained by reaction of the substituted phosphoric acidwith an aromatic heterocyclic, tertiary, organic nitrogen base.Advantageous results may be obtained in the process according to theinvention when salts or complexes with pyridine, quinoline, isoquinolineor derivatives thereof or such bases substituted by, for example, loweralkyl, halogen, acyl, acylamido, cyano, carboxy, or aldoximino areemployed.

The salts for use in the process according to the invention may bederived from proportions of the acid and the base such that one or moreof the acidic function(s) is exactly neutralized by the base. Generally,we prefer to use molar equivalents of the base and the acid. If desired,however, molar proportions other than those specified above may be used,for example, a less than molar quantity of nitrogen base may be employedso that, in addition to the salt, the catalyst also comprises some freeacid. Alternatively, a more than molar quantity of nitrogen base may beemployed to produce a salt the average composition of which correspondsto a material intermediate to a monoor di- (nitrogen base) salt. Thebase may be used in excess of the total molar requirement to neutralizethe acid function(s) but should not be used in large excess e.g. itshould generally not be used in amounts of 5 molar excess and greater.

The optimal ratio of the acid base will depend on various factorsincluding the nature of the acid and of the base as well as the natureof the penicillin oxide. The optimal ratio may be ascertained bypreliminary trial and experiment.

The salts employed in the process according to the invention constitutea further embodiment thereof. An important salt according to theinvention is pyridinium 2,2,2-trichloroethyl dihydrogen phosphate.

The process according to the invention is conveniently carried out in anorganic solvent since one may regulate more exactly reaction conditionssuch as temperature. Ordinarily, the penicillin oxide will be insolution in the organic solvent. The solvent should be substantiallyinert to the penicillin oxide used in the process and to thecephalosporin produced by the process.

Solvents which may be used include those described in U.S. Pat. No.3,275,626 and other publications describing the rearrangement reaction.However, particularly suitable solvents include ketones boiling at from75-120C (e.g. 100-120C), esters boiling at from 75-140C (e.g. 100-130C),dioxan and diethylene glycol dimethyl ether (diglyme). Illustrative ofthose ketones and esters that may be used in the process according tothe invention are aliphatic ketones and esters having appropriateboiling points including ethyl methyl ketone, isobutyl methyl ketone,methyl n-propyl ketone, n-propyl acetate, n-butyl acetate, iso-butylacetate, sec-butyl acetate and diethyl carbonate.

The time for achieving optimum yields by the process according to theinvention varies according to the particular solvent employed. Therearrangements are conveniently carried out at the boiling point of thechosen solvent and, for those solvents boiling in the lower part of theranges quoted above, correspondingly longer reaction times, e.g. up to48 hours, may be required than for those solvents boiling at highertemperatures. Rearrangements in dioxan generally require times of 3-24hours, preferably 5-12 hours, to achieve optimum results whereas thosecarried out in methyl isobutyl ketone generally require times of 1-8hours. The yields in the rearrangements are dependent, but to a lesserextent, on the concentration of the catalyst in the solvent,correspondingly longer reaction times being required for lowerconcentrations of catalyst. In general acid catalysts require longertimes than the corresponding salts with nitrogen bases.

We particularly prefer to use dioxan as the organic solvent. Penicillinoxides can be dissolved in this solvent in high concentration and ingeneral there is no falling off of yield with increase of concentrationup to concentrations of the order of 35 percent.

The quantity of the catalyst used should not generally exceed 1.0 moleper mole of the penicillin oxide; however, we generally prefer to usecatalysts in proportions of from 0.01 to 0.2 mole per mole of penicillinoxide. A preferred catalyst proportion is 0.06 mole per mole.

The catalysts used in the process according to the invention producecomparatively little color during the rearrangement as compared withsimilar rearrangements carried out in the presence of an acid catalystsuch as a hydrocarbyl sulphonic acid. By-products commonly formed withsuch acid catalysts appear to only a much smaller extent with. thecatalysts herein described. The use of salts in particular, has thepractical advantage that, under our preferred conditions, it isunnecessary to use decolorizing agents and acid binding agents beforeremoving the reaction solvent.

The appropriate time interval for any particular reaction may bedetermined by testing the reaction solution by one or more of thefollowing procedures:

1. Thin layer chromatography, for example on silica gel, developing witha 2:1 mixture of benzene and ethyl acetate and rendering the spotsvisible by treatment with an iodine/azide solution (Russell, Nature,1960, 186, 788). Where, for example, the starting material is the2,2,2-trichloroethyl ester of 6fl-phenylacetamidopenicillanic acidlfi-oxide, the product (R 0.64) gives an orange/brown color whereas thestarting material (R 0.5) gives a dark yellow color.

2. Determination of the rotation after suitable dilution of .thereaction mixture with for example, chloroform. Using the same startingmaterial as in (l) the rotation drops to between about a third to abouta quarter of the initial value.

3. Determination of the ultraviolet spectrum of a sample of the reactionmixture suitably diluted with ethyl alcohol. Using the same startingmaterial as in (l) the calculated value for E 264 nm rises to about fora successful reaction. Absorption maxima at higher wavelengths arepreferably low or absent. This determination cannot be adopted whenketonic solvents are used as the reaction media.

Although satisfactory yields can be obtained by carrying out thereaction under normal reflux, it may be possible to improve the yieldsby inserting a desiccating agent (e.g. alumina, calcium oxide, sodiumhydroxide or molecular sieves) which is inert to the solvent in'thereflux return line to remove water formed during the reaction.Alternatively the waterformed during the reaction may be removed by theuse of a fractionating column, the water formed being removed byfractional distillation.

After completion of the reaction the catalyst may be removed eitherbefore or after concentrating the reaction mixture. If the reactionsolvent is immiscible with water, the salt can be removed by a simplewashing procedure. On the other hand, if the reaction medium is misciblewith water a convenient purification technique is to remove the reactionsolvent (this may be achieved by distillation under reduced pressure)and then to purify the residue by any convenient process e.g.chromatography on silica gel.

If an acid catalyst has been used in the process ac cording to theinvention it is desirable to remove this before concentrating thereaction mixture. As before, if the reaction solvent is immiscible withwater, the catalyst can be removed by a simple washing procedure. On theother hand, if the reaction medium is miscible with water a convenientmethod of removing the acid catalyst is to treat the reaction mixturewith a finely divided neutralizing agent such as calcium carbonate ormagnesium oxide, followed by filtration in the presence of a filter aid.The reaction solvent is then removed, conveniently under reducedpressure, and the residue purified by any convenient process e.g.chromatography on silica gel.

It has been found, however, that the degree of conversion achieved bythe process according to the invention may be such that complicatedpurification procedures can be dispensed with and the product isolatedin a substantially pure condition by pouring the reaction mixture intowater, filtering off the product and if desired further purifying byrecrystallization from, or slurrying with, a suitable solvent.

When using, for example, a mono-pyridinium salt of a mono-substitutedphosphoric acid in dioxan solution, it is necessary only to evaporateoff the solvent and to crystallize the product from a suitable solventin order to obtain a high yield of substantially pure product.

A color removal step e.g. by means of charcoal may be employed; howeverthis is not normally necessary under the preferred conditions of theprocess according to the invention.

The penicillin oxide used as starting material in the process accordingto the invention may be derived from a salt of6B-phenylacetamidopenicillanic acid or of6B-phenoxyacetamidopenicillanic acid obtained, for example, from afermentation process, by esterification of the carboxyl group at the3-position of the penicillanic acid and oxidation of the sulphur atom atthe 1- position. Alternatively the penicillin oxide may be obtained from6B-aminopenicillanic acid by acylation of the amino group at theofi-position, esterification of the carboxyl group at the 3-position,and oxidation of the sulphur at the l-position.

The oxidation may be carried out as described by Chow, Hall and Hoover(J. Org. Chem. 1962, 27, 1381). The penicillin compound'is mixed withthe oxidizing agent in an amount such that at least one atom of activeoxygen is present per atom of thiazolidine sulphur. Suitable oxidizingagents include metaperiodic acid, peracetic acid, monoperphathalic acid,mchloroperbenzoic acid and t-butylhypochlorite, the latter beingpreferably used in admixture with a weak base, e.g. pyridine. Excessoxidizing agents may lead to the formation of 1,1-dioxide. The l-oxidemay be obtained in the 0:- and/or B-form.

Acyl groups at the 6B-amino position of the penicillin oxide may be anydesired acyl group but should preferably be reasonably stable under theconditions of the rearrangement.

Conveniently the acyl group at the 6B-position is that of a penicillinobtained by a fermentation process e.g. phenylacetyl or phenoxyacetyl.Such a group may not be the desired group in the cephalosporinend-product but this can be introduced by subsequent transformationsdescribed below. Another group which may conveniently be used is theformyl group.

Alternatively, the acyl group at the 6B-position of the penicillin oxidemay be that desired in the cephalosporin compound, e.g. a thienylacetylor phenylglyoxylyl group, or it may be a precursor for the desired acylgroup e. g. an acyl group containing a protected functional group suchas a protected amino group. An example of such an acyl group is aprotected B-aminophenylacetyl group.

The amine protecting group is conveniently one which can subsequently beremoved by reduction or hydrolysis without afiecting the rest of themolecule, especially the lactarn and 7B-amido linkages of the resultingcephalosporin compound. A similar protecting group may also be used asthe esterifyinggroup at the 3-C OOH position and both groups can besimultaneously removed as described below. An advantageous procedure isto remove both groups at the last stage in the sequence. Protectedgroups include urethane, arylmethyl (e.g. trityl)-amino,arylmethyleneamino, sulphenylamino and enamine types. Such groups can ingeneral be removed by oneor more reagents selected from dilute mineralacids, e.g. dilute hydrochloric acid, concentrated organic acids, e.g.concentrated acetic acid, trifluoroacetic acid, and liquid hydrogenbromide at very low temperatures, e.g. 80C. A convenient protectinggroup is the tertiary butoxycarbonyl group, which is readily removed byhydrolysis with dilute mineral acid, e.g. dilute hydrochloric acid, orpreferably with a strong organic acid, (e.g. formic acid ortri-fluoroacetic acid), e.g. at a temperature of 0-40C., preferably atroom temperature l5 25C). Another convenient protecting group is the2,2,2-trichloroethoxycarbonyl group which may be split off by an agentsuch as zinc in acetic acid, formic acid, lower alcohols or pyridine.

The ester of the penicillanic acid is preferably formed with an alcoholor phenol which may readily be split off, e.g. by hydrolysis orreduction, at a later stage to yield the subsequently formed ceph-3-emcompound as the free acid. Alcohol and phenol residues which may readilybe split off include those containing electron-attracting substituentsfor example sulpho groups and esterified carboxyl groups, these groupsmay be subsequently split off by alkaline reagents. Benzyl ando-benzyloxyphenoxy ester groups may be removed by hydrogenolysisalthough this may involve catalyst poisoning. A preferred method ofremoval involves acid cleavage and groups which may be removed by acidcleavage include adamantyl, t-butyl, benzyl residues such as anisyl andthe residues of alkanols containing electron donors in the a-positionsuch as acyloxy, alkoxy, benzoyloxy, substituted benzoloxy,

halogen, alkylthio, phenyl, alkoxyphenyl or aromatic heterocyclic. Theseradicals may be derived from benzyl alcohols such as p-methoxybenzylalcohol, di-pmethoxyphenylmethanol, triphenylmethanol, diphenylmethanol,benzoyloxymethanol, benzoylmethanol, pnitrobenzyl alcohol and furfurylalcohol.

Alcohol residues which may be readily split off subsequently by areducing agent are those of a 2,2,2- trihalogenoethanol, e.g.2,2,2-tricholoroethanol, pnitrobenzyl alcohol or 4-pyridylmethanol.2,2,2- Trihalogenoethyl groups may conveniently'be removed byzinc/acetic acid, zinc/formic acid, zinc/lower a1- cohol orzinc/pyridine or by chromous reagents; pnitrobenzyl groups mayconveniently be removed by hydrogenolysis and 4-pyridylmethyl groups mayconveniently be removed by electrolytic reduction.

Where the ester group is subsequently removed by an acid catalyzedreaction, this may be effected by using formic acid or trifluroaceticacid (preferably in conjunction with anisole) or alternatively by usinghydrochloric acid e.g. in admixture with acetic acid.

We particularly prefer to use those penicillin oxides having adiphenylmethoxycarboxyl, a 2,2,2- trichloroethoxycarbonyl, at-butoxycarbonyl, a pnitrobenzyloxycarbonyl, benzoylmethoxycarbonyl orp-methoxybenzyloxycarbonyl group at the 3-position in the processaccording to the invention because the ceph-3-em compounds formed fromesters of this type do not appear to undergo appreciable A Aisomerization in the de-esterification reaction.

Where the product of the rearrangement is a 7,8- acylamidoceph-3-emcompound not having the desired acyl group, the 7B-acylamido compoundmay be N- deacylated, if desired after reactions elsewhere in themolecule, to yield the corresponding 7B-amino compound and the latteracylated with an appropriate acylating reagent.

Methods of N-deacylating cephalosporin derivatives having 7B-acylamidogroups are known and one suitable method comprises treating a7B-acylamidoceph-3- em-4-carboxylic acid ester with an imide-halideforming component, converting the imide halide so obtained into theimino ether and decomposing the latter. If desired, the ester group maybe split off by hydrolysis or hydrogenolysis to yield the 4-carboxylicacid. Suitable readily removable ester groups are described above.

Suitable imide halide forming components include acid halides derivedfrom the phosphorous acids, the preferred compounds being the chloridessuch as, for example, phosphorous oxychloride or phosphorouspentachloride.

This method of N-deacylation is described in greater detail in BelgianPatent No. 719,712.

N-Deformylation of a 7,8-formamido group may be effected with a mineralacid at a temperature of minus to 100C, preferably +15 to 40C. Aconvenient reagent for the N-deformylation is concentrated hydrochloricacid in methanol or, preferably, in dioxan or tetrahydrofuran sinceundesirable transesterification reactions that tend to occur in methanolare thereby avoided.

In order that the invention may be well understood the followingexamples are given by way of illustration only.

In the examples, unless otherwise stated, thin layer chromatography(TLC) was carried out on silica gel using a mixture of benzene and ethylacetate (2:1) as the developing solvent and detecting the spots withiodine/azide solution.

EXAMPLE 1 2,2,2-Trichloroethyl 6B-phenylacetamidopenicillanate lfl-oxide(9.64 g.; 20 m.moles), phenyl dihydrogen phosphate (0.244 g.; 1.4m.moles) and pyridine (0.114 ml; 1.4 m.moles) were boiled under refluxin dry peroxide-free dioxan (50 ml.) and the condensate was run througha column of desiccant (Woelm basic alumina 30 g.) before being returnedto the reaction flask. The progress of the reaction was followed by TLC.After 8 hours reflux no starting material remained. The solution wascooled to ca 30 and poured into water (82.5 ml.) with stirring. Thesolid was isolated by filtration, washed with water ml.) and the dampcake slurried with a 3:1 mixture of ethanol/water (30 ml.). The solidwas filtered off, washed with the 3:1 ethanol/water (30 ml.) and driedin vacuo at 40 to give 2,2,2-trichloroethyl 3-methyl-7B-phenylacetamido-ceph-3-em-4-carboxylate (7.396 g.; 80.6 percent oftheory) m.p. 159 60 (corrected); [:1] D +54 (c, 0.8 in CHCl A (ethanol)264 nm E 1 percent EXAMPLE 2 2,2,2-TrichloroethylGB-phenyla'cetamidopenicillanate IB-oxide (19.28 g.; 40 m.moles),pyridinium 2,2,2-trichloroethyl dihydrogen phosphate (0.494 g.; 1.6m.moles) and pyridine (0.13 ml.; 1.6 m.moles) were refluxed in dioxan(96.4 ml.) as described in Example l. Reaction was complete after 5%hours. The cooled solution was poured into stirred water ml.). The solidwas isolated by filtration and the damp cake slurried with isopropylalcohol (41.5 ml.). The solid was filtered off and washed with a 2.3:1mixture of isopropyl alcohol to water (50 ml. slurry wash, 75 ml.displacement wash) and dried at 40 in vacuo to give 2,2,2-trichloroethyl3-methyl-7B-phenylacetamidoceph-3-em-4-carboxylate (15.22 g.; 82 percentof theory), m.p. 161 4 (corrected [a},,+ 54 (c, 0.8 in CHCl X (ethanol)264 nm (E 132.5).

EXAMPLE 3 2,2,2-Trichloroethyl 6B-phenylacetamidopenicillanate 1B-oxide(9.64 g.; 20 m.moles) and pyridinium 4-nitrophenyl dihydrogen phosphate(0.298 g.; l m.mole) were refluxed 1n dioxan (50 ml.) as described inExample 1.

After 6% hours reflux the solvent was evaporated under reduced pressureand the residue triturated with warm industrial methylated spirits (IMS)(10 ml.). The mixture was stored at 0 for 2 days. The solid was filteredoff, washed with IMS (10 ml. slurry wash, 10 ml. displacement wash) anddried in vacuo at 40 to give 2,2,2-trichloroethyl3-methyl-7B-phenylacetamidoceph-3-em-4-carboxylate (6.71 g.; 72.3percent of theory) m.p. 162 6 (corrected) [01],, +53.4 (c, 1.0 in CHCl X(ethanol) 264 nm (Elcm'l Percent A second crop (0.7 g.; 7.5 percent oftheory) was obtained by concentration of the bulked lMS liquors m.p. 160(corrected) [07],, +53.5 (c, 0.9 in CHCl A (ethanol) 264 nm (E 135.8).

at 40 in vacuo to give 2,2,2-trichloroethyl dihydrogen phosphatepyridine salt (580 g.; 93.6 percent of theory). Recrystallization fromethanol gave material (394 g.; 68 percent recovery), m.p. 101 103.

5 Found: C, 27.3; H, 3.0; N, 4.5; Cl, 34.2.

EXAMPLE 4 c,n,,o,r-11=c1 requires: c, 27.3; H, 2.9; N, 4.5; 01, 34.5

2,2,2-Trichloroethyl 6B-phenylacetamidopenicil- P lanate IB-oxide (9.6g.; 20 m.mole) and pyridinium 2- The followmg Salts were P p e 111Slmllal' chloromethyl-4-nitrophenyl dihydrogen phosphate 10 manner-(0.277 g.; 0.8 m.moles) were refluxed in dioxan (50 0 ml.) as describedin Example 1. The react on was complete after 5 hours. The cooledsolution was 1 poured into stirred water (82.5 ml.). The product wasisolated in an identical manner to that described in Ex- TABLE 1 ample 3to glve, after drying at 40 1n vacuo, 2,2,2- trichloroethyl 3-methyl-7B-phenylacetamidoceph-3- Acid B S l em-4-carbox-ylate (7.30 g.; 78.5percent of theory Example gg f f lgg' m.p. 160 163 (corrected), [01],,52.3 (c, 0.6 in CHCl A (ethanol) 264 nm(E 135). 011101 EXAMPLE 5 9 N01Pyridine 2,2,2-Trichloroethyl 6B-pheny1acetamidopenicillanate lB-oxide(100g.; 0.2076 mole), pyridinium 10 2,2,2-trichloroethyl dihydrogenphosphate (3.84 g.; I

TABLE 1.Continued Salt M 12)., Found Requires Ex (corn) C IT CI NFormula 6 H BT 1? 123-5 50.3 4.7 4.4 C11H5104NP 59.4 47 46 13744 41.8 as10.1 7.7 CnHnOsNgPCl 41.6 10.2 81 131-5 44.4 3.8 0.3 CnHnOoNzP 44.3 a 79 4 12.5 m.moles) were refluxed in dioxan (500 ml.) as EXAMPLE 11described 1n Example 1. Reaction was complete after Example I wasrepeated using quinolinium phenyl 6% hours. The product was isolated inthe manner d d E l 2 t 2 2 2 t hl th 1 3 dihydrogen phosphate(preparatron glven 1n Example escn e m xamp e gwe Owe y 7 8) (0.6064'g.;2 m. moles). The reaction time was 7%methyl-75-phenylacetam1doceph-3-em-4-carboxy1ate o hours. The work-upwas performed in a s1m1lar fashion (79.3 g., 82.3 percent theory), m.p.161 4 (coro to give 2,2,2-tr1chloroethyl 3-methyl-7B-phenrected) [01],,52 (c, 0.5 in CHCl A (ethanol) l 6 88 74 9 264 m (Elm 1 new", 1315)ylacetam1doceph-3-em-4-carboxy ate g.,

' percent of theory), m.p. 160 162 (corrected); [01],, EXAMPLE6 53.2"(c, 0.8 in CI-lCl X (ethanol) 264-11m. 1m."" 2,2,2-Tr1chloroethyl6B-phenylacetam1dopemcillanate lfl-oxide (100 g.; 0.2076 mole),pyridinium EXAMPLE 12 2,2,2-tr1ch1oroethyl dihydrogen phosphate (3.84g.', I 12.5 m.mole) were refluxed in dioxan (500 ml.) as 9 f Y B'Pdescribed in Example 1. On completion of the reactionylacetamldopemclnanate lle'oxlde (9-54 8' O the cooled mixture was addedover 20 minutes to l dlhydrogen Phosphate 8G stirred water (1 1.). Theresulting solid was removed by and P 8- 1 mmole) Wlth condifiltration,washed with water and dried at 40 in vacuo Hons as Exampl6 1 a ptechnique as in to give 2,2,2-trichloroethyl 3-methyl-7B-phenample 2 sZJJ-HIChIOIOeIhYI y B-P ylacetamidoceph-3-em-4-carboxylate as a paleyellow ylacetamldoceph3'em'4'carboxylate 4 P solid g.; '98 percent oftheory), m.p. 152 5 (corcent Y), -P- 161-30 10 rected), (11],, 59.8 (c,0.6 in C1-1C1 1, (ethanol) In e); Am. (ethanol) 264 nm m... 264 nm (E123). 132).

EXAMPLE 7 60 EXAMPLE l3 Orthophosphoric acid ester salts 2,2,2- Reactionof 1 Y B'P T i hl h l dih d phosphate ylacetamidopenicillanate IB-oxide(9.64 g.; 20 monopyridine salt m.moles), o-carboxyphenyl dihydrogenphosphate A solution of 2,2,2-trichloroethyl dihydrogen 65 8 mg-; lIII-mole) and py g-; l m.mole) phosphate (460 g.) in isopropyl ether (2l.) was stirred and pyridine ml.) was added from a dropping funnel over15 minutes, then the solid isolated by filtration, washed with isopropylether- (500 ml.) and dried with conditions as in Example 1 and work-uptechnique as in Example 2 gave 2,2,2-trichloroethyl-3methyl-7B-phenylacetamidoceph- 3-em-4-carboxylate (6.7 g.', 72.2 percent oftheory), m.p. 154 9C (corrected); [01],,

53.6 (c, 0.8 in CHCl X (ethanol) 264 nm; (B flercent EXAMPLE 14 A repeatof Example 13 using more pyridine (157 mg.; 2 m.moles) gave2,2,2-trichloroethyl 3-methyl-7B- phenylacetamidoceph-3-em-4-carboxylate(6.7 g.; 72.2 percent of theory), mp. 155 9 (corrected); [01],, 54.4 (c,0.8 in Cl-lCl X (ethanol) 264 nm; (E percent 13 3 EXAMPLE l52,2,2-Trichloroethyl 6B-phenylacetamidopenicillanate IB-oxide (9.63 g.;20 m.mole) was heated under reflux in dioxan (50 ml.) with2-chloromethyl-4- nitrophenyl dihydrogen phosphate (214 mg.; 0.8m.mole). After 8 hours, when the reaction was complete, the solution wascooled and poured into stirred water (82.5 ml.). The solid was filteredoff and washed with isopropanol/water (2.311, 1 slurry wash 125 ml. andl displacement wash 60 ml.). After drying the solid (7.6 g.; 81.8percent, mp 155 9 (corrected) was re-washed with ether (30 ml.) anddried in vacuo overnight to give 2,2,2-trichloroethyl 3-methyl-7B-phenylacetamidoceph-3-em-4-carboxylate (7.0 g.; 76 percent oftheory), mp. 160 62 (corrected), [01],, 53.3 (c, 0.8, CHCl A (EtOH) 264nm, E Percent v EXAMPLE 16 2,2,2-Trichloroethyl6B-phenylacetamidopenicillanate 1B-oxide (100 g.; 0.208 mole) and 2,2,2-trichloroethyl dihydrogen phosphate (3.84 g.; 0.08 mole equivalent) wereboiled under reflux in dioxan (500 ml.). The reaction was complete after10% hours. The mixture was cooled and poured into water and theresulting crude product slurried with aqueous isopropyl alcohol anddried in vacuo to give 2,2,2-trichloroethyl3-methyl-7B-phenylacetamidoceph-3-em-4-carboxylate (76 g.; 78.9 percentof theory) m.p. 157-59 (corrected), [04],, 54 (c, 0.8 in Cl-lCl X (EtOH)264 nm, E 134.

EXAMPLE 17 To 2,2,2-trichloroethyl GB-phenylacetamidopenicillanateIB-oxide (9.64 g. 20 m.mole) in dioxan (50 ml.) was added 4-nitrophenyldihydrogen phosphate (438 mg. 2 m.mole) and the solution was refluxed ina manner such that the condensed dioxan ran down through a column ofWoelm basic alumina (30 g.) before returning to the reaction vessel.After 6 hours reflux the solution was decanted and evaporated to drynessunder reduced pressure. The residue was triturated with warm IMS (10ml.), and the solution refrigerated overnight.

The solid was filtered off, washed with IMS (slurry 10 ml., displacement10 ml.) and dried in vacuo at 40C to constant weight to give2,2,2-trichloroethyl 3- methyl-7B-phenylacetamidoceph-3-em-4-carboxy1ate(5.65 g.; 60.8 percent theory) m.p. 1616; [011 51 (CHCl 0.9); X 264 nm,E 136 (ethanol).

EXAMPLE 18 To 2,2,2-trichloroethy1 6B-phenylacetamido penicillanatelB-oxide (19.28 g. 40 m.mole) in dioxan ml.) was added pyridine (158 mg.2 m. mole) and pyridinium 4-nitrophenyl hydrogen phosphate (596 mg. 2m.mole) and the stirred solution was refluxed for 6% hours in a mannersuch that the condensed dioxan vapors ran down through a column of Woelmbasic alumina (30 g.) before returning to the reaction vessel.

The solution was added dropwise with stirring to water (165 ml.) and theresulting precipitate was filtered off, washed with water and dried invacuo at 40C. to constant weight to give a yield of 17.43 g. (94percent). The total crude product was twice slurried with a 7:3isopropanolzwater mixture (53 ml.) and displacement washed on the filtertwice with a similar mixture (25 ml.). The solid was dried in vacuo at40C. to constant weight to give 2,2,2-trichloroethyl 3-methyl-7B-phenylacetamidoceph-3-em-4-carboxylate m.p.

160-3AC; [a],, 54.8 (CHCl 0.6); X 264 nm, E

1 percefll 2 thanol).

EXAMPLE 19 To 2,2,2-trich1oroethyl 6B-phenylacetamidopenicillanatelB-oxide (9.64 g., 20 m.mole) in dioxan (50 ml.) was added bis(4-nitrophenyl) hydrogen phosphate (340 mg. 1 m.mole) and the solutionwas refluxed in a manner such that the condensed dioxan vapors ranthrough a column of alumina before returning to the reaction vessel. Thesolution was refluxed for 31%hours, decanted hours, decanted andevaporated to dryness under reduced pressure. The residue was trituratedwith IMS (10 ml.), refrigerated and the solid filtered off, washed withIMS (5 ml. slurry, 5 ml. displacement) and dried in vacuo at 40 C. toconstant weight to give 2,2,2-trichloroethyl3-methyl-7B-phenylacetamidoceph-3-em-4-carboxylate (2.88 g.; 31.1percent of theory) m.p. 1614C, [01],, 53.6(CHCl 0.8),). 264 nm E137.8(ethanol).

EXAMPLE 20 To 2,2,2-trichloroethyl 6B-phenylacetamidopenicillanatelfi-oxide (8.57 g., 17.8 .mole) in dioxan (43 ml.) was added bis(p-nitrophenyl)hydrogen phosphate (303 mg. 0.89 m.mole) and pyridine(70.4 mg., 0.89 m.mole) and the solution was refluxed for nine hours ina manner such that the condensed dioxan vapors ran through a column ofWoelm basic alumina (30 g.) be fore returning to the reaction vessel.The solution was evaporated to dryness under reduced pressure, theresidue triturated with warm IMS (10 ml.) and refrigerated overnight.The solid was filtered off, washed with IMS (10 ml. slurry, 10 ml.displacement) and dried in vacuo at 40C to constant weight, to give2,2,2-trichloroethyl 3-methyl-7B-phenylacetamidoceph-3-em-4-carboxylate(3.948 g., 42.56 percent) m.p. 1625C, [01],, 52.8 (CHCl 1.0), X 264 nm E134 (ethanol).

EXAMPLE 21 p-Methoxybenzyl GB-phenylacetamidopenicillanate IB-oxide(9.41 g., 20 m.mole), monopyridinium 2,2,2- trichloroethyl dihydrogenphosphate (0.665 g., 2.16 m.mole) and pyridine (0.316 g., 4 m.mole) wereboiled under reflux in dry peroxide-free dioxan (200 ml.) so that thecondensate passed through molecular sieves (Linde 4A 1/16 inch 40 g.before returning to the reaction flask. TLC (benzene-ethyl acetatezlzl)showed that no starting material was present after 16 hours. Thesolution was cooled and the dioxan was evaporated under reducedpressure. The residue was crystallized from boiling methanol (225 ml.)to give cream needles of p-methoxybenzyl3-methyl-7B-phenylacetamidoceph-3-em-4-carboxylate (6.70 g., 74.0percent) m.p. l5ll53[a],, 39 (c, 0.82 in CHCl A (ethanol) 226 nm (E 365)and 268 nm (E f 170). Evaporation of the filtrate and crystallization ofthe residue from methanol ml.) gave a second crop (0.50 g., 5.5percent), m.p. l48-153[a] 36 (c, 1.13 CHCl X (ethanol) 226 nm (E m 349)and 268 nm (E 158).

We claim:

1. In a process for the preparation of 7B-acylamido-3-methyl-ceph-3-em-4-carboxylic acid esters by heating a6B-acylamidopenicillanic acid l-oxide ester in the presence of acatalyst, the improvement which comprises employing as catalyst, acatalyst selected from the group consisting of a lower alkyl, phenyllower alkyl or phenyl dihydrogen phosphate or such a dihydrogenphosphate in which the lower alkyl, phenyl lower alkyl or phenyl groupis substituted by at least one of a halogen atom or a nitro group; adiphenyl hydrogen phosphate or such a hydrogen phosphate in which thenitrophenyl dihydrogen phosphate trichloroethyl dihydrogen phosphate.

4. A process as defined in claim 1 wherein said base is an unsaturatedheterocyclic tertiary base selected from the group consisting ofpyridine, quinoline, isoquinoline, benzimidazole and lower alkylderivatives thereof.

5. A process as defined in claim 1 wherein said nitrogen base isselected from the group consisting of aniline, an N-lower alkyl aniline,a chloroaniline, .a lower alkyl aniline, a hydroxy aniline, a loweralkoxy aniline, a nitroaniline and a carboxyaniline, the namedsubstituted anilines being otherwise unsubstituted.

6. A process as defined in claim 1 wherein said salt is obtained by thereaction of one molar equivalent of the dihydrogen phosphate or hydrogenphosphate with one or two molar equivalents of said nitrogen base orabout two molar equivalents of said nitrogen base with one molarequivalent of the dihydrogen phosphate or hydrogen phosphate.

7. A process as defined in claim 1 in which a proportion of said saltnot exceeding 1.0 mole per mole of penicillin oxide is used.

8. A process as defined in claim 7 wherein the proportion of said saltis from 0.01 to 0.2 mole per mole of penicillin oxide.

9. A process as defined in claim 1 wherein a solvent selected from thegroup consisting of dioxan, ethyl methyl ketone, isobutyl methyl ketone,methyl npropyl ketone, n-propyl acetate, n-butyl acetate, isobutylacetate, sec-butyl acetate, diethyl carbonate and diethylene glycoldirnethyl ether is employed.

10. A process as defined in claim 9 in which the reaction is effected atthe boiling point of the solvent and wherein a desiccating agent, whichis inert under the reaction conditions, is inserted in a reflux returnline to remove water formeg daring the reaction.

and 2,2,2-

2. A process as defined in claim 1 wherein said catalyst is saiddihydrogen phosphate.
 3. A process as defined in claim 1 wherein saidcatalyst is a dihydrogen phosphate selected from the group consisting ofphenyl dihydrogen phosphate, p-nitrophenyl dihydrogen phosphate,2-chloromethyl-4-nitrophenyl dihydrogen phosphate and2,2,2-trichloroethyl dihydrogen phosphate.
 4. A process as defined inclaim 1 wherein sAid base is an unsaturated heterocyclic tertiary baseselected from the group consisting of pyridine, quinoline, isoquinoline,benzimidazole and lower alkyl derivatives thereof.
 5. A process asdefined in claim 1 wherein said nitrogen base is selected from the groupconsisting of aniline, an N-lower alkyl aniline, a chloroaniline, alower alkyl aniline, a hydroxy aniline, a lower alkoxy aniline, anitroaniline and a carboxyaniline, the named substituted anilines beingotherwise unsubstituted.
 6. A process as defined in claim 1 wherein saidsalt is obtained by the reaction of one molar equivalent of thedihydrogen phosphate or hydrogen phosphate with one or two molarequivalents of said nitrogen base or about two molar equivalents of saidnitrogen base with one molar equivalent of the dihydrogen phosphate orhydrogen phosphate.
 7. A process as defined in claim 1 in which aproportion of said salt not exceeding 1.0 mole per mole of penicillinoxide is used.
 8. A process as defined in claim 7 wherein the proportionof said salt is from 0.01 to 0.2 mole per mole of penicillin oxide.
 9. Aprocess as defined in claim 1 wherein a solvent selected from the groupconsisting of dioxan, ethyl methyl ketone, isobutyl methyl ketone,methyl n-propyl ketone, n-propyl acetate, n-butyl acetate, iso-butylacetate, sec-butyl acetate, diethyl carbonate and diethylene glycoldimethyl ether is employed.
 10. A process as defined in claim 9 in whichthe reaction is effected at the boiling point of the solvent and whereina desiccating agent, which is inert under the reaction conditions, isinserted in a reflux return line to remove water formed during thereaction.